Multimorbidity and Comorbidity in Atrial Fibrillation and Effects on Survival: Findings from UK Biobank Cohort

Problem

Atrial Fibrillation (AF) is the commonest sustained cardiac arrhythmia. Multimorbidity, defined as the presence of two or more long-term condition (LTC), or comorbidity defined as the presence of one more LTC in addition to an index condition, is very common in people with AF. The relationship between multimorbidity and comorbidity with mortality in people with AF remains unclear.

Approach

The objective of this study is to examine the number and type of comorbid LTCs, and their associations with all-cause mortality in UK Biobank participants with AF. Data were reviewed from 495,010 participants in UK Biobank, an anonymised community research cohort, aged between 40-69 years, recruited between 2006-2010 from across the UK. Self-reported comorbidities (n=42) were identified in 3651 people with AF. Hazard Ratios (HRs) examined associations between number and type of comorbid LTC and all-cause mortality. Results were adjusted for age, sex, socio-economic status, smoking and anti-coagulation status. All participants with self-reported AF at the time of baseline assessment were included in the cohort. All-cause mortality was available for a median follow-up period of 7 years (Interquartile range 76 months to 93 months) by linking UK Biobank records with national mortality records.

Findings

3651 participants (0.7% of the study population) reported AF; mean age of participants was 61.9 years. The rate of all-cause mortality in those with AF was 6.7% (248 participants) at 7 years. Nearly 79% of participants with AF reported having at least one other LTC, while 55% reported one other cardiometabolic condition. Among AF participants, those with 4 or more comorbidities had a 3.5 times higher risk of mortality than those with none. Comorbid heart failure was associated with significantly higher risk of all-cause mortality (HR 2.96; 95% confidence intervals (CI) 1.83-4.80), while presence of comorbid stroke was not associated with higher risk of mortality. Among non-cardiometabolic conditions, presence of COPD (HR 3.31; 95% CI 2.14-5.11) and osteoporosis (HR 3.13; 95% CI 1.63-6.01) were associated with a significantly higher risk of all-cause mortality.

Consequences

Survival in middle-aged individuals with self-reported AF is strongly correlated with level of multimorbidity; this group should be targeted for interventions to optimise their management which in turn may potentially reduce the impact of their comorbidities on survival. Future AF clinical guidelines need to place greater emphasis on the issue of co-morbidity.